Let ) be a random variable with the following probability distribution. Value x of X P(X =x) 10 0.45 20 0.15 30 0.05 40 0.30 50 0.05 Complete the following. (If necessary, consult a list of formulas.) (a) Find the expectation E (X) of X. E(X) = I X 5 ? (b) Find the variance Var(X ) of X. Var(X) =